This invention relates to a cured chlorinated polyethylene composition having superior mechanical properties such as low permanent compression set and other superior properties such as resistances to weather, ozone, chemicals, oils and to heat and reduced coloration, and also to an uncured chlorinated polyethylene composition which exhibits such improved properties after curing. The invention also relates to a process for curing an uncured chlorinated polyethylene composition by heating, which can impart these improved properties to chlorinated polyethylene at relatively low temperatures and within relatively short periods of time without involving any operational troubles.
Chlorinated polyethylene, particularly, substantially amorphous rubbery chlorinated polyethylene having a chlorine content of 25 to 45%, is a useful elastomeric material, and upon being sufficiently cured, becomes a rubbery material having superior mechanical properties, and resistances to heat, weather, ozone, chemicals and oil.
In order to cure chlorinated polyethylene, various methods using peroxides, thiourea derivatives, and thiuram sulfides, for example, have heretofore been suggested. The methods relying on the use of thiourea derivatives and thiuram sulfides suffer from a very slow rate of curing, and can scarcely afford cured products having satisfactory properties as rubber.
The method using peroxides is considered to be able to give the best cured product among these methods. However, the peroxides cause various troubles during their handling or with regard to curing conditions, such as the handling danger of low temperature-decomposable peroxides, the disadvantage of the rise of the curing temperature caused by high temperature-decomposable peroxides, and the obstruction of curing in the presence of oxygen. Accordingly, it has been very difficult by the conventional art to provide a cured chlorinated polyethylene composition which is useful as a rubbery material having satisfactory properties.